1. Field of the Invention
The present invention relates to a winding layer pitch compensation for an air-core reactor which has at least two concentric winding layers spaced apart radially from one another.
2. Description of the Related Art
Air-core reactors are used in energy supply networks and, by contrast with oil-insulated reactors, are “dry-insulated reactors”, in which the insulation is provided by solid insulation and sufficient air clearances and creepage distances and which as a rule also do not contain any ferromagnetic core, i.e., their central air space is free.
The concentric winding layers of the air-core reactor are each held at their upper and lower axial ends by a holder star, which is composed of a number of star-shaped arms disposed radially. Instead of a one-piece holder star, a plurality of individual star sheets can also be used in each case, which only lie in the area below and above the winding layers, in order to save on star sheet material. The holder stars or star sheets lying opposite one another are tensioned in relation to one another in such cases with the aid of spacer strips or tension bandages extending between the winding layers, in order to hold the winding layers. During winding of the reactor, the star sheets and spacer strips are simultaneously used as winding aids, in that the lower star sheets are initially tensioned on a turning device and the winding layers are then constructed thereon, where a set of spacer strips is installed between them in each case.
As a result of the different conductor cross sections in the individual winding layers different pitches and/or axial installation heights of the individual winding layers are produced in such cases, which require winding layer pitch compensation. Here, compensation sheets are inserted between the star sheets lying opposite one another axially and the winding layer lying between said sheets, which support the winding layers in relation to the star sheets and center them in an axial direction.
Conventional compensation sheets are relatively complex parts because the height to be compensated for between a star sheet and a winding layer varies depending on the circumferential location of the reactor, radial location of the winding layer and conductor cross-section of the winding layer, which even for a single coil dimensioning demands a plurality of different individually-calculated compensation sheets. For different coil dimensionings, the required variations in compensation sheets multiply.